Demi-Fraser Broth Base (7656) - mibius

DEMI-FRASER BROTH BASE (7656)
Intended Use
Demi-Fraser Broth Base is used with ferric ammonium citrate for the selective enrichment of Listeria
species.
Product Summary and Explanation
Listeria monocytogenes, described in 1926 by Murray, Webb, and Swann, is a widespread problem in public
health and food industries. 1 This organism has the ability to cause human illness and death, particularly in
immunocompromised individuals and susceptible pregnant women. 2 Epidemiological evidence from
outbreaks of listeriosis indicate the principle route of transmission is via the consumption of foodstuffs
contaminated with Listeria monocytogenes. 3 Implicated vehicles of transmission include turkey frankfurters,
coleslaw, pasteurized milk, Mexican style cheese and pate′. 4 Listeria species are ubiquitous in nature,
present in a wide range of unprocessed foods and in soil, sewage, and river waste. 5
Demi-Fraser Broth Base is a modification of Fraser Broth Base, developed by Fraser and Sperber, 6 and used
for the rapid detection of Listeria from food 7 and environmental samples. In Demi-Fraser Broth Base, the
nalidixic acid and acriflavine concentration have been reduced in accordance with AFNOR guidelines. 8
Identification of Listeria is based on successful isolation of the organism, biochemical characterization, and
serological confirmation.
Principles of the Procedure
Enzymatic Digest of Casein, Enzymatic Digest of Animal Tissue, Beef Extract, and Yeast Extract provide
nitrogen, vitamins, and minerals in Demi-Fraser Broth Base. The Phosphates are the buffering agents.
Sodium Chloride maintains osmotic balance. Differentiation is aided by including Ferric Ammonium Citrate in
the final medium. Since all Listeria species hydrolyze esculin, the addition of ferric ions to the medium will
detect the reaction. A blackening of the medium by cultures containing esculin hydrolyzing bacteria is the
result of formation of 6,7-dihydroxycoumarin that reacts with ferric ions. 6 Selectivity is provided by the
presence of Lithium Chloride, Nalidixic Acid, and Acriflavin in the formula. The high salt tolerance of Listeria
is used to inhibit growth of enterococci.
Formula / Liter
Enzymatic Digest of Casein...................................................... 5 g Supplement / 10 mL
Enzymatic Digest of Animal Tissue .......................................... 5 g 5% Ferric Ammonium Citrate, 10 mL
Beef Extract .............................................................................. 5 g Filtered sterilized aqueous solution /L
Yeast Extract ............................................................................ 5 g
Sodium Chloride ..................................................................... 20 g
Disodium Phosphate.............................................................. 9.6 g
Monopotassium Phosphate ................................................. 1.35 g
Esculin ...................................................................................... 1 g
Acriflavin ............................................................................ 0.012 g
Nalidixic Acid ..................................................................... 0.010 g
Lithium Chloride........................................................................ 3 g
Final pH: 7.2 ± 0.2 at 25°C
Formula may be adjusted and/or supplemented as required to meet performance specifications.
Precautions
1. For Laboratory Use.
2. HARMFUL. Harmful if swallowed, inhaled, or absorbed through the skin. Skin irritation may be severe.
Irritating to eyes, skin, and respiratory system. May cause central nervous system effects.
Directions
1. Dissolve 55 g of the medium in one liter of purified water.
2. Heat gently in a 50°C waterbath to completely dissolve the medium. DO NOT OVERHEAT.
3. Autoclave at 121°C for 15 minutes. Cool to room temperature.
4. Aseptically add 10 mL of a filtered sterilized 5% aqueous solution of ferric ammonium citrate.
PI 7656, Rev 04, 10/24/04

Quality Control Specifications
Dehydrated Appearance: Powder is homogeneous, free flowing, and light beige.
Prepared Appearance: Prepared medium is golden yellow with an amber opalescent top and clear to
slightly hazy.
Expected Cultural Response: Cultural response in Demi-Fraser Broth Base at 35°C after 18 - 48 hours
incubation.
Microorganism
Escherichia coli ATCC® 25922
Listeria monocytogenes ATCC® 7644
Listeria monocytogenes ATCC® 15313
Staphylococcus aureus ATCC® 25923
The organisms listed are the minimum that should be used for quality control testing.
Response
Inhibited
growth w / blackening
growth w / blackening
suppressed at @ 24 hours; recovery at 48 hours
Test Procedure
To isolate Listeria monocytogenes and other Listeria spp., refer to appropriate references. 7,8,9
4
Results
Listeria is presumptively indicated by the blackening of Demi-Fraser Broth Base after 18 - 48 hours
incubation at 35°C. For further identification and confirmation of Listeria species, consult appropriate
references. 7,8,9 Rapid slide and macroscopic tube tests can be used for definitive serological identification.
Storage
Store sealed bottle containing the dehydrated medium at 2 - 30°C. Once opened and recapped, place
container in a low humidity environment at the same storage temperature. Protect from moisture and light.
Expiration
Refer to expiration date stamped on the container. The dehydrated medium should be discarded if not free
flowing, or if appearance has changed from the original color. Expiry applies to medium in its intact container
when stored as directed.
Limitations of the Procedure
Due to nutritional variation, some strains may grow poorly or fail to grow on this medium.
Packaging
Demi-Fraser Broth Base Code No. 7656A 500 g
7656B 2 kg
7656C 10 kg
References
1. Murray, E. G. D., R. A. Webb, and M. B. R. Swann. 1926. A disease of rabbits characterized by large mononuclear leucocytosis
caused by a hitherto undescribed bacillus Bacterium monocytogenes. J. Path. Bacteriol. 29:407-439.
2. Monk, J. D., R. S. Clavero, L. R. Beuchat, M. P. Doyle, and R. E. Brackett. 1994. Irradiation inactivation of Listeria
monocytogenes and Staphylococcus aureus in low and high fat, frozen and refrigerated ground beef. J. Food Prot. 57:969-974.
3. Bremer, P. J., and C. M. Osborne. 1995. Thermal-death times of Listeria monocytogenes in green shell mussels prepared for hot
smoking. J. Food Prot. 58:604-608.
4. Grau, F. H., and P. B. Vanderlinde. 1992. Occurrence, numbers, and growth of Listeria monocytogenes on some vacuumpackaged
processed meats. J. Food Prot. 55:4-7.
5. Patel, J. R., C. A. Hwang, L. R. Beuchat, M. P. Doyle, and R. E. Brackett. 1995. Comparison of oxygen scavengers for their
ability to enhance resuscitation of heat-injured Listeria monoytogenes. J. Food Prot. 58:244-250.
6. Fraser, J., and W. Sperber. 1988. Rapid detection of Listeria in food and environmental samples by esculin hydrolysis. J. Food
Prot. 51: 762-765.
7. Lee, W. H., and D. McClain. 1994. Laboratory Communication No. 57, U.S.D.A., F.S.I.S. Microbiology Division, Bethesda, MD.
8. L’association francaise de normalisation (AFNOR). 1993. Food Microbiology-Detection of Listeria monocytogenes-Routine
Method, V 08-055. AFNOR, Paris, France.
9. Murray, P. R., E. J. Baron, M. A. Pfaller, F. C. Tenover, and R. H. Yolken (eds.).1995. Manual of clinical microbiology, 6 th ed.
American Society for Microbiology, Washington, D.C.
Technical Information
Contact Acumedia Manufacturers, Inc. for Technical Service or questions involving dehydrated culture media preparation or
performance at (517)372-9200 or fax us at (517)372-2006.
PI 7656, Rev 04, 10/24/04